1. Field of the Invention
This invention relates to a switch for a direction indicator of a vehicle, and more particularly to improvements of a switch for a direction indicator suitable for use in a motor car, comprising: a bracket operationally associated with a lever for operating the direction indicator and rotated through an predetermined angle in accordance with a direction indicated; a ratchet opposed to the main body of said bracket through a steering wheel shaft, opposite end portions of which are constantly biased in a direction of being engaged with opposite end portions of the main body of said bracket, and rotated by said bracket through a predetermined angle in dependence on the direction indicated; and a cancel cam provided on the periphery thereof with projections capable of releasing the engagement between the main body and the end portion of said bracket in response to the rotation of a steering wheel, biased in a direction of being engaged with the steering wheel in a condition of having a slight clearance in the direction of rotation and rotated along with the steering wheel.
2. Description of the Prior Art
In general, in a vehicle such as a motor car, a direction indicator such as direction indicating lamps are normally used for the purpose of indicating the direction when said vehicle changes its running direction. The switch for the direction indicator is operated prior to the control of a steering wheel when the vehicle and the like turns the running direction, and it is desirable that, after the vehicle changes the running direction by controlling the steering wheel and the like, the switch is automatically returned to its original position when the steering wheel and the like is restored. Consequently, heretofore, such a construction has been adopted that a built-in lever switch for controlling actions of a plurality of contacts through vertical and lateral motions of a lever is provided and said switch is automatically returned to the original position by the utilization of the motion of the steering wheel upon operating the steering wheel.
One example of the conventional switch for a direction indicator of a vehicle of the type as described above is shown in FIGS. 1 and 2. In the drawing, designated as reference numeral 10 is a vehicle body such as a steering column; 12 a steering wheel provided at the forward end of said steering column for controlling the moving direction of the vehicle; 14 a lever for operating the direction indicator projecting sidewise from the steering column; 16 a bracket operationally associated with said lever 14 for operating the direction indicator, adapted to be rotated through a predetermined angle in dependence on the direction indicated and a main body of which is formed into a substantially `U` letter shape; 18 substantially a letter `C` shaped ratchet opposed to the main body of said bracket 16 through a steering wheel shaft, opposite end portions of which are constantly biased in a direction of being engaged with opposite ends of the main body of said bracket 16 by a compression spring 20, and rotatable by said bracket 16 through a predetermined angle in dependence on the direction indicated; 22 a cancel cam provided on the periphery thereof with projections 22a capable of releasing the engaged condition between the main body and the end portions of said bracket 16 in response to the rotation of the steering wheel 12, biased by a compression spring 24 in a direction of being engaged with the steering wheel 12 in a condition of having a slight clearance in the direction of rotation, and rotated along with the steering wheel 12; 26 a click motion ball for controlling the motion of said ratchet 18 and said bracket 16 to be stopped with a click motion at a right-turn indicating state R, a non-indication state N or a left-turn indicating state L, respectively; and 10a a stopper formed on the steering column and the like for receiving said click motion ball 26 and positively stopping said bracket 16 and said ratchet 18 in accordance with said respective conditions.
In addition, the cancel cam 22 and the steering wheel 12 are arranged such that cancel pins 22b formed at an abutting surface of the cancel cam 22 are inserted into cancel pin holes 12a formed at an abutting surface of the steering wheel 12, whereby the rotation of the steering wheel 12 is imparted to the cancel cam 22 in a condition of having a slight clearance in the direction of rotation.
In the conventional switch for the direction indicator of the vehicle of the type as described above, the click motion ball 26 of the ratchet 18 is engaged with a central recess of the stopper 10a in the non-indication state N, where the lever for operating the direction indicator is not operated, as shown in FIG. 2. At this state, if the lever 14 for operating the direction indicator is turned in the counterclockwise direction in the drawing to turn the running direction to the left, then the bracket 16 and ratchet 18 is rotated likewise in the counterclockwise direction as shown in FIG. 3, whereby the click motion ball 26 of the ratchet 18 is brought into engagement with an upper recess of the stopper 10a. In this condition of indicating the left turn, if the steering wheel 12 is rotated in the counterclockwise direction to actually change the running direction of the vehicle to the left, then the projections 22a of the cancel cam 22 release the engagement between the lower end of the ratchet 18 and the lower end of the main body of the bracket 16 as shown in FIG. 4. If the steering wheel 12 is rotated further, then the disengagement is discontinued, whereby the lower end portions of the ratchet 18 and the lower end portions of the main body of the bracket 16 are engaged with each other as shown in FIG. 3. If the steering wheel is rotated still further, the engagement between the upper end portions of the ratchet 18 and the upper end portions of the main body of the bracket 16 is released likewise and returned to the original condition. At this time, the click motion ball is in a condition of being received in the upper recess of the stopper 10a, and hence, the operating position of the lever 14 for operating the direction indicator is not changed. If the steering wheel 12 is rotated in the clockwise direction in the drawing to change the running direction of the vehicle to return to the straightly advancing condition, the projection 22a pushes the upper end portion of the ratchet 18 in the clockwise direction. As a result, since the projection 22a releases the engagement between the bracket 16 and the ratchet 18, and since a dividing portion between the upper recess and central recess of the stopper 10a is low enough for the click motion ball 26 to pass, the ratchet 18 is automatically restored to a condition where the click motion ball 26 is engaged with the central recess of the stopper 10a through the agency of the click motion ball 26, i.e., a position where the lever for operating the direction indicator is in the non-indication state.
As described above, the conventional switch for the direction indicator of the vehicle has such a characteristic feature that, in spite of the number of rotations of the steering wheel, the lever for operating the direction indicator is held in the original indicating state, and, when the steering wheel is returned to restore the original running direction, the switch is automatically restored to the non-indication state. However, in the case where the steering wheel is rotated to a direction to which the running direction is to be changed in the state shown in FIG. 4, i.e., the state where the indication of the direction is sent out, when the ratchet 18 passes over the projection 22a of the cancel cam 22, striking noises take place between the ends of the ratchet 18 and bracket 16 thus raising a problem that an unpleasant feeling is given to the driver of the vehicle. Accordingly, hereto, there has been such a practice that a grease of high viscosity is applied onto the abutting surfaces of the ratchet 18 and bracket 16 for the purpose of arresting sounds. However, said grease tends to flow out from the required portion due to heat and mechanical friction during use, with a result that the effect of arresting noises does not last long. Furthermore, the so-called cock grease generally used as the water-proof grease at joint portions of water pipes is adopted as a sound arresting grease. Said cock grease is of high viscosity, with a result that, in use for a mass production line, when the grease is attached to the portions, where application of the grease is not required at all, such as the lever for operating the direction indicator and vehicle body, it is very difficult to remove the grease therefrom, thereby frequently presenting problems in respect of product quality. Further, even in the case where a grease of high viscosity is used, when the grease is used in the switch for the direction indicator, the ambient temperature around which is elevated to as high as 70.degree. to 90.degree. C., it is not avoidable for the grease to be lowered in viscosity, and consequently, there has been presented such a problem that an effective residual presence of the grease at the abutting surfaces cannot be expected for a long period of time.